1) Field of the Invention
The present invention relates generally to agricultural implements such as a cotton harvester, and, more specifically, to structure for automatically aligning a row unit with a row of crop to be harvested.
2) Related Art
Harvesters such as cotton pickers include a plurality of row units supported on a transversely extending header frame and spaced so that each unit receives an individual row of crop. For optimum harvesting efficiency, the row of crop must be aligned with a row receiving area on the row unit. Sometimes the number of row units on the harvester differs from the number of planter rows on the planter used to plant the crop, and it becomes necessary for the harvester to simultaneously harvest rows planted in two different passes of the planter. The spacing between the rows of one planter pass and one or more adjacent rows (sometimes termed "guess rows") may vary considerably, and unless there is continuous adjustment of the row harvesting units for the guess rows, row misalignment and crop loss occur.
Various devices have been proposed to maintain row harvesting units in alignment with the rows of crops. U.S. Pat. No. 5,343,677 assigned to Case Corporation shows a system with a sensor for each of the movable row units connected to a controller which in turn controls an activation device to move the individual units to maintain the units in alignment with the crop rows. U.S. Pat. No. 5,782,072 issued to H. Wayne Matthews shows another row unit tracking system wherein a computer receives a signal from a sensor associated with one of the row units and calculates the amount of deviation between the crop row and the center of the row unit. A control signal is sent to a solenoid valve to actuate a cylinder which aligns the row unit with the row. Such systems have provided improved row alignment but are relatively complicated and expensive and require electronic controls. Some of the systems require expensive proportional valves. A simpler, more straight forward alignment system which is less expensive than most previously available alignment systems is desirable.